Pennington Impounding Reservoir

Design and construct improvement works to Pennington reservoir, which impounds water from Rathmoss Beck behind an earth embankment dam approximately 22m high and 165m long.

It was built in 1879 to provide a water supply to Barrow in Furness and the surrounding district.

Works included providing additional wave wall protection to prevent overtopping of the dam crest, improvements to the spillway arrangements to provide safe freeboard to discharge off a PMF and provision of support to the existing slate block walls in the upper section of the spillway.

A new reinforced earth bund was installed to protect the downstream embankment from erosion, 77m long with a top level 1.5m above the existing spillway wall formed by regarding the ground and forming a bund wall of imported sub-base. The internal faces of the bund are lined with interlocking cable tied revetment blocks and reinforced concrete.

Additional safety measures required the installation of 80m of GMS hand railing to the top of the existing spillway walls.

Refurbishment of the spillway channel, incorporating the construction in RC of a new spillway base (630m²) and walls (490m²), the existing slate block walls were retained and a geocomposite drainage blanket was used to separate the slate blocks from the new reinforced concrete walls.

Construction of new RC wave walls (250m²), clad both sides with dry stone facing and copings was also carried out, requiring the localised removal and re-laying of the stone pitching.

Due to the sensitive location of the site significant third party and environmental management and liaison was undertaken.